Cummins Fault Code 598: Electrical Charging System Voltage Low - Critical Level

598 on Cummins engines means: Electrical Charging System Voltage Low - Critical Level. The failure mode (FMI 1) is “data valid but below normal operating range (most severe)”.

Lamp: Red

Stop engine now – damage imminent.

Code details

Manufacturer: Cummins
Applies to: Cummins QS-series electronic engines
Fault code: 598
J1939 SPN: 167
FMI: 1 — Data valid but below normal operating range (most severe)
J1587 PID / SID: P167
Engine models: QSM11, QSX15

What to do next

Treat this as a stop-level fault: shut down safely and get the truck checked before running it further.
Read active and inactive codes with the OEM service tool and note the occurrence count.
FMI 1 tells the shop the type of failure to test for: data valid but below normal operating range (most severe).
Have a heavy-duty diesel technician confirm the fault against the engine or chassis service manual before replacing parts.